1. Field of the Invention
The present invention relates to an apparatus for selectively controlling a plurality of electric motors and the like, and more particularly to such an apparatus which is operable to selectively drive individual electric motors which are coupled to a work object, the apparatus herein described having particular utility when employed in combination with a machine for blending numerous materials into an end product having a desired composition, and wherein the apparatus is further adapted to selectively control the individual electric motors in a predetermined fashion as to speed and general operation by using a single variable speed motor drive.
2. Description of the Prior Art
In the production of various products which may contain various pharmaceutical components such as, for example, feeds for livestock which may contain selective volumes of drug supplements, assorted machinery has been designed, developed and manufactured with the idea in mind of eliminating as much manual labor as possible. Micro-ingredient batching systems, as they have come to be known, have been characterized heretofore by highly labor intensive operations and therefore the direct cost of labor and equipment that were required to effectively combine a variety of constituent elements was generally substantial. A variety of devices have been developed and employed over the years for this purpose. More particularly, the prior art is replete with a multiplicity of prior art references which are directed to automatic batch weighing systems such as that exemplified by U.S. Pat. No. 4,222,448 to Sunkle, et al. and which are adapted to compound batches of a plurality of constituents in accordance with a predetermined formula.
Heretofore many of the prior art devices have utilized hydraulic motors for driving the selected work objects which are integral subassemblies of these prior art batching machines. Hydraulic motors have been the selection of choice for a number of important reasons. For example, and one of the most important reasons for selecting hydraulic motors has usually been the concern regarding the cost of manufacturing the batching machines. As should be understood, the speed and the actuation of hydraulic motors may be selectively controlled by a relatively inexpensive value assembly whereas, in the case of electric motors, these devices may be adjusted as to speed only by using a variable speed motor drive which is quite costly. Further, electric motors were often not employed due, in part, to the dust environment in which these batching or blending machines normally operate; it being understood that electric motors could create an explosion hazard.
While the batching and blending systems and machines utilized heretofore have operated with some degree of success, they have exhibited numerous shortcomings which have detracted from their usefulness. For example, and while hydraulic motors normally operate quite efficiently, they often require more than just periodic maintenance. For example, and regardless of the application, labor intensive tasks such as replacing leaky fittings and filters or changing hydraulic fluid, replacing worn or burst hoses or worn pumps and the like, normally requires a substantially constant and diligent preventive maintenance program. Further, and regardless of the preventive maintenance applied, most hydraulic motors will eventually leak, thereby creating various hazards. In addition to the foregoing and regardless of the quality of the hydraulic valves employed to control the individual hydraulic motors, such valve assemblies will experience wear and will eventually leak. When such leaking occurs, the affected hydraulic motor, which may be disposed in driving relationship relative to a conveyor on a prior art batching assembly, may begin to slowly turn, thereby adding material(s) to an end product without an operator's knowledge. As should be readily apparent and if the selected material contains a drug, the final end product may contain extremely hazardous levels of this same material. If this end product is a feed supplement, for example, the ingestion of same could have deleterious health consequences for the livestock consuming it. The use of electric motors in such a batching system would have a desirable benefit inasmuch as there is no likelihood that an electric motor would drive a conveyor when no power is being applied to the selected motor, thereby reducing the likelihood that errors would occur in preparing a batched end product.
Still another problem encountered in the prior art batching machines and related assemblies which have been designed for such use is the propensity for such mechanisms to exhibit a characteristic inability to cooperate with other devices near to or connected with the batching machine.
Therefore, it will be seen that the prior art batching machines do not balance the practical needs of the micro-ingredient batching industry and the interrelated parameters of efficiency, cost effectiveness and safety which is particularly critical to the profitability of such operations.
Therefore, it has long been known that it would be desirable to have an apparatus for selectively controlling a plurality of electric motors at a variety of different speeds and which are adapted to drive individual work objects, and which could be employed in a wide variety of different industrial environments, and on an assortment of different machines and other devices, and which could be manufactured and purchased at a relatively moderate cost and which is both highly efficient in operation, and which further reduces to an absolute minimum the assorted problems associated with the use of hydraulic motors in connection with related prior art assemblies.